Single facer with belt adjusting device

Abstract: A single facer which includes a rotating corrugating roll (24) for corrugating a medium; an endless belt (23) for pressing a liner against the medium on the corrugating roll; at least a pair of belt rolls (21, 22) for running the endless belt; and a direction adjusting mechanism (25) for changing the running direction of the endless belt with respect to the rotating shaft of the corrugating roll within the running plane of the endless belt to correct zigzag or sideway motion of the belt occurring while the belt is running; a detector (30) for detecting sideway displacements of the endless belt; a computer (35) for computing a positional correction to be made in the width direction based on a signal from the detector; and a controller (31a) for controlling the direction adjusting mechanism (25) based on a value computed by the computer. In addition to the adjustment of the running direction of the endless belt, a tension balance between the opposite edges of the endless belt can be corrected by adjusting the relative angle between the shafts of the belt rolls.

Description: The present invention relates to a single facer including a rotating corrugating roll for corrugating a medium and for carrying a medium with paste being applied to top portions of corrugation thereof; an endless belt for pressing a liner against the medium on the corrugating roll, and at least a pair of belt rolls for giving tension to the endless belt and for running it; the single facer having a belt adjusting device which is configured so as to correct a zigzag or meandering movement of an endless belt in the cross direction and/or shearing deformation of the endless belt and resulting contraction of the belt width occurring as the endless belt runs applying bonding pressure on paper webs being processed. Conventionally, when manufacturing an endless belt which runs around a plurality of rolls in sequence into an endless form, it is very difficult to make the lengths of belt edges on opposite sides to be exactly the same dimension with high accuracy. Moreover, elongation of the belt occurs variably at right and left side edges over extended periods of use, or various factors such as slight inaccuracy of parallelism among the rolls at the time of manufacture may cause relative shifts between the two side edges of the belt. As a result, the endless belt may move toward one side in the roll axis direction or tend to move in a zigzagging manner. With relative differences in the amount of running motion (lengthwise shifts) of the side edges of the belt, shrinkage of the belt width in the cross direction may arise. This tendency of shrinkage is more expressed when the slip of the belt with respect to the rolls is less or, in other words, when the tension of the belt is higher. A conventional method for correcting such tendency in dynamic belt motion has been to visually check the condition of the belt and then change the angle of the rotating shaft of some rolls to manually adjust the tension at each side edge of the belt. With this conventional method, however, human attention is required frequently, and a high level of technical skill is needed in correcting the shift caused by various factors. Under these circumstances, some measures have been desired for easily correcting shifts in belt position at each side edge of the belt without human intervention. On a single facer, corrugation is formed on a medium between a rotating corrugating roll 54 and another corrugating roll 54' engaging with each other, as shown in FIG. 10. Paste is applied to the top portions of corrugation on the corrugated medium, and a liner is bonded to the medium by pressing the liner against the medium by means of an endless belt 53 to produce a one-side corrugated fiberboard which has a flat surface on one side and a corrugated surface on the other side. The endless belt 53 is driven by at least a pair of parallel belt rolls 51 and 52. FIG. 11 is a view for illustrating the occurrence of zigzag or sideway movement while a power-transmitting endless belt is running and a device for adjusting the zigzag movement. As described above, it is difficult to manufacture the endless belt 53, which runs around a plurality of belt rolls 51 and 52, so as to make the lengths of opposite side edges thereof to be exactly the same. Also, as the endless belt 53 is used over extended periods of time, two side edges of the belt become elongated differently or poor parallelism of the rolls 51 and 52 causes the endless belt 53 to shift in the cross direction (i.e., the direction along the roll axis) or move in a zigzagging manner while the endless belt 53 is running. As a result, not only the belt 53 collides with a housing 59, but also the manufacture of single-sided corrugated fiberboard at the edge portion cannot be done because the position of the belt 53 shifts beyond the width of the product. To solve these problems, for endless belts in general, after the conditions of zigzag or sideway movement and shift are checked by eyes or by a detector, an adjustment is made by manually changing the tension of each side edge of the belt. This adjustment, which is made by an operator, is done by changing the direction of the rotating shaft of the roll 52 by means of a cylinder 56a or 56b in the plane in which the belt runs. When such an adjusting method alone is applied to a single facer, however, deviations in relative movement between opposite side edges tend to occur easily because the belt is very wide relative to its length, unlike common endless belts. As a result, the belt width W decreases, or the life of the belt is shortened due to shear deformation in the plane of the belt. Also, for such a wide belt, the position of the belt on the roll tends to shift in the cross direction because there normally exist some differences in belt length between the side edge portions even if no relative differences in belt tension exist between the opposite side edge portions of the belt. A single-faced corrugated cardboard sheet making machine (single facer) with the features of the introductory portion of claim 1 is described in EP 0 492 310 A1. An endless belt is set to run around a pair of belt rolls and presses a liner against a core paper web applied with paste running over a corrugated roll. While one of the belt rolls is fixedly journalled and cannot change its position against the corrugating roll, the other may be adjusted as to its direction of the axis and generation of pressing force towards the corrugated roll by an adjustment cylinder. This kind of adjustment is insufficient to avoid sideway and zigzag movement of the belt with regard to the corrugating roll. Therefore, on the single facer, in addition to the device for adjusting the tension of the side edge portion, a different type of devices have been desired for belt adjustment to solve the above-described problems inherent in the single facer. An object of the present invention as defined in the appended claims is to provide a single facer having a belt adjusting device which can correct a movement of the endless belt in the belt width direction, zigzag or sideway movement, and shear deformation such as shrinkage of belt width in the plane of the belt, considering the above-described problems inherent in the single facer. A further object of the invention is to provide, in place of the conventional device in which the tension is corrected by manually adjusting the relative angle between the rotating shafts of the rolls after the belt condition is checked visually, a belt adjusting device which is configured so as to automatically correct such relative differences in belt tension between its opposite side edges. Further aspects of the present invention are the application of the technique relating to the automatic adjusting device of an endless belt to a single facer. According to the invention, the running direction of the endless belt can be deviated from the direction perpendicular to the rotational axis of the corrugating roll while the angle between the rotating shafts of the pair of belt rolls is substantially maintained. In this way, the belt keeps running without one side of the endless belt being advancing or retarding with respect to the other side, and the shrinkage of the belt width can be reduced or stopped. According to Qne aspect of the invention, at least one pair of belt rolls among the rolls which are in contact with the endless belt are commonly tilted with respect to the corrugating roll in the plane of these rolls, by which the endless belt can be moved in the width direction to automatically correct the zigzag movement. A further aspect of the invention provides a single facer in which the adjustment of tension can be made at the right and left side edges of the belt in addition to the adjustment of the running direction of the belt with respect to the axial direction of the corrugating roll. For this purpose, a mechanism is installed to change the relative directions of the rotating shafts of the belt rolls with respect to each other to adjust the relative tension between the opposite side ecges of the endless belt. By this mechanism, a pair of belt rolls deviate from the ordinary parallel relationship therebetween. Various embodiments of the direction adjusting mechanism are defined in the subclaims. The belt adjusting device includes detection markings located near opposite side edges of an endless belt set around a plurality of rolls; detectors for detecting the positions of the detection markings in the direction of belt run; a control unit which accepts outputs of the detectors; and a direction adjusting device for changing the direction of rotational axis of at least one of the rolls; wherein the detector detects a positional shift between opposite side edges of the belt in the direction of belt run, and the direction adjusting device is controlled by the control unit in accordance with outputs from the detectors in order to change the direction of the rotational axis of at least one of the rolls. One of adjusting mechanisms for correcting imbalance in belt tension between right and left edges of the belt is a device for changing the bridge length, such as a hydraulic unit, which can be installed in a bridge connecting the rotating shafts of a belt roll pair, so that the angle formed by the rotating shafts of the two belt rolls is adjusted. Also, the directions of the rotating shafts of two belt rolls are changed relatively by operating a moving device, which is installed on the rotating shaft of the belt roll, independently for each rotating shaft, by which imbalance in tension between the right and left edges of the belt can be adjusted. By the use of the above-mentioned belt adjusting device, at least one pair of belt rolls which give tension to the endless belt and run the belt are tilted relatively in the plane including these belt rolls, while the angle between the rotating shafts of the rolls or their parallelism is maintained, by which the angle with respect to the corrugating roll can be adjusted. Thereupon, the belt can be moved in the width direction on the belt roll. The shift or zigzag movement of the belt can be corrected. According to the invention, varying imbalance of belt tension between the right and left belt edges, in addition to the shift and zigzag movement of belt, can be corrected. Also, by applying the automatic adjustment techniques discussed, such adjustment can be made automatically without relying on the skills of an operator. Various exemplary embodiments of the invention are illustrated in the accompanying drawings. FIG. 1 is a schematic top plan view showing one embodiment of a single facer; FIG. 2 is an enlarged view for illustrating the adjusting function of the endless belt in the single facer of FIG. 1; FIG. 3 is a schematic top plan view showing another embodiment of a single facer; FIG. 4 is a schematic plan view showing further embodiment of a single facer; FIGS. 5A and 5B are schematic views showing a modification of the single facer shown in FIGS. 1, 3, and 4. FIG. 6 is a schematic plan view showing another embodiment of a single facer; FIG. 7 is a schematic plan view showing another embodiment of a single facer; FIG. 8 is a schematic plan view showing a further embodiment of a single facer; FIG. 9 is a schematic plan view showing a still further embodiment of a single facer; FIG. 10 is a side view of a conventional belt type single facer; and FIG. 11 is a plan view of a mechanism for adjusting an endless belt on the conventional single facer. FIGS. 1 to 4 show the basic configuration and function of a single facer in accordance with one aspect of the invention. In FIG. 1, a pair of belt rolls 21 and 22 supports and drives an endless belt 23, and presses the endless belt 23 against a corrugating roll 24. The bridges 27a and 27b connect the rotating shafts of the belt rolls 21 and 22. The angle adjusting cylinder 25 rotates the bridges 27a and 27b around the supporting point 32 via a link 26. Reference numeral 29 indicates a part of the housing of the single facer. A liner is bonded, by means of the endless belt 23, to a medium which is corrugated by the corrugating roll 24 (as done by rolls 54 and 54' in FIG. 10) and to the top portion of which is applied paste, so as to form a one-side corrugated sheet. During this process, when zigzag movement of the endless belt 23 is detected, the angle adjusting cylinder 25 is operated so that the running direction of the endless belt 23 is tilted by an inclination angle Θ 1 . of the running direction of the belt with respect to the direction perpendicular to the rotating shaft of the corrugating roll 24 within the plane including the rotating shafts of the belt rolls 21 and 22. In other words, a certain angle Θ 1 is formed between the rotating shaft of the corrugating roll 24 and the rotating shafts of the belt rolls 21, 22. Thus, the zigzag movement of the endless belt 23 is corrected. This correcting action will be described with reference to FIG. 2. In FIG. 2, when the running direction of the endless belt 23 is tilted by an angle Θ 1 with respect to the direction perpendicular to the rotating shaft of the corrugating roll 24, a force F 0 in the axial direction of the corrugating roll is produced on the endless belt 23 by a force F 1 in the running direction and a force F 2 in the rotating direction caused by a frictional force between the corrugating roll 24 and the endless belt 23. This resultant force Fo corrects the zigzag movement. When the endless belt 23 begins to shift upward as shown in FIG. 1, the tilting of the belt rolls 21 and 22 with respect to the corrugating roll 24 results in a correcting force F 0 downward as shown in FIG. 2 so as to correct such movement. This force becomes larger as the contact surface pressure between the corrugating roll 24 and the endless belt 23, the contact area (contact length) between them, a coefficient of friction, and the tilt angle Θ 1 increase. Therefore, if sufficiently high values are given to these factors, the endless belt 23 in FIG. 1 moves downward, so that the position of the endless belt 23 is corrected. FIGS. 3 and 4 show other means for providing an angle to the endless belt 23. In FIG. 3, one end of each of the rotating shafts of the belt rolls 21, 22 is mounted independently at the supporting point 32 rotatably within the running plane of the endless belt 23. The other ends of the rotating shafts of the belt rolls 21, 22 are connected together by a bridge 27, and the angle of the belt rolls 21, 22 with respect to the corrugating roll 24 is adjusted by moving the bridge 27 by means of an angle adjusting cylinder 25. In FIG. 4, one end of each rotating shaft of the belt rolls is mounted in the same as shown in FIG. 3, but the other ends are independently provided with angle adjusting cylinders 25. The angle adjusting cylinders 25 may be replaced with electromechanical means using a motor and a screw, or the like. FIGS. 5A and 5B shows a configuration in which a roll 40 is installed in addition to a pair of belt rolls 21 and 22 for running the endless belt 23. Even if the number of rolls for guiding the endless belt 23 is increased, the above-mentioned correcting operation remains the same. In FIGS. 5A and 5B, the rotating shaft of the roll 40 is kept in parallel with the rotating shaft of the corrugating roll 24, independently of the direction of the pair of belt rolls 21 and 22. However, the roll 40 may also be tilted in association with the belt rolls 21 and 22 with the same effect. In the next embodiment, an automatic control unit is added to the inclination angle adjusting means in the embodiment shown in FIG. 1. FIG. 6 shows the construction of this embodiment. Reference numerals 21-29, and 32 denote the same elements as those shown in FIG. 1, and the explanation of these elements is omitted. A zigzag movement detector 30 detects the positions of edge portions of the endless belt 23. This detector 30 uses conventionally known means such as a transmission type photoelectric tube to detect shifts of the endless belt 23 in the width direction. A control unit 31a controls an angle adjusting cylinder 25 on the basis of the signal given from the zigzag movement detector 30. This control unit 31a calculates a required amount of correction on the basis of the shift of the endless belt given from the zigzag movement detector 30, and generates a signal for operating the angle adjusting cylinder on the basis of the correction amount. Next, an embodiment of the invention in which belt tension adjusting means is added to the embodiment shown in FIG. 1 is described. FIG. 7 shows this embodiment. As described above, for an endless belt used in the single facer, the adjustment of tension imbalance between opposite side edges of the endless belt is desirable because such an endless belt has a particularly large width. Tension adjusting cylinders 28a, 28b are provided further to adjust the right and left balance of the belt tension. In FIG. 7, tension at each side edge of the endless belt 23 is detected by conventional means (not shown), and tension adjusting cylinders 28a and 28b are operated manually or automatically on the basis of the detected tension value to adjust the tension of the endless belt 23. In this case, the zigzag movement adjustment is basically made independently of the tension adjustment. Specifically, with the positional relation of the belt rolls 21 and 22 being fixed after tension adjustment has been made, the angle adjusting cylinder 25 is operated to correct zigzagging movement. In this case, automatic control means shown in FIG. 13 may be incorporated. At this time, the positional relation of the rotating shafts of the belt rolls 21 and 22 should be parallel for the zigzag movement adjustment, but actually they are not always parallel because the tension adjustment has been made. Here, for the detection of belt tension, detectors used for, finding relative shifts between the two opposite sides of the endless belt in the running direction as shown in FIGS. 1-3 and 6 can also be sued. Next, a still further embodiment of a single facer in accordance with the invention will be described with reference to FIG. 8. This embodiment is provided with an automatic control system in which the zigzag movement adjustment and the tension adjustment of the endless belt 23 are performed independently. Comparing with the embodiment in FIG. 6, this embodiment is characterized by the addition of a tension adjustment mechanism and a tension adjustment control system. In FIG. 8, detection pieces, detection marks, etc. 33a and 33b (i.e., detection markings) are installed at both side edges of the belt 23, by which positional shifts in the running direction between the side edges of the belt are detected by transmission type photoelectric tubes 34a and 34b which serve as detecting means together with detection markings 33a and 33b. Then, hydraulic pressures to the right and left tension adjusting cylinders 28a and 28b are adjusted via a control unit 31b. In FIG. 8, the hydraulic pressure in the cylinder 28b is increased relatively with respect to the hydraulic pressure of the cylinder 28a to tilt the belt roll 21 with respect to the belt roll 22. The construction of the embodiment shown in FIG. 6 can be used in combination with the tension adjusting device shown in this embodiment. Various types of detection markings and detectors can be used in this embodiment; the present invention is not limited to the particular examples thereof. In the construction of a still further embodiment in FIG. 8, after zigzag movements and/or correction required therefor, and positional shifts in the running direction between opposite side edges of the belt and/or correction required therefor are found, calculation is made using these values to determine desired amounts of correction. As described above, a wide belt, such as an endless belt used in the single facer, is difficult to manufacture with sufficient accuracy to make its peripheral lengths exactly equal. For this reason, there is a tendency for the belt to move or meander transversely or to have relative shifts in the running direction between opposite side edges. Such a tendency is corrected according to the embodiment in FIG. 8 in the following manner: The position shift is corrected by the relative difference ΔP in tension given to one side edge with respect to the other edge, and the zigzag movement is corrected by a tilt angle Θ 1 of the belt given with respect to the rotational axis of the corrugating roll. However, if a tension difference ΔP is given to correct the positional shift in the running direction between the two side edges of the belt, a zigzag movement sometimes occurs. If a belt tilt angle Θ 1 is given to correct the zigzag movement, a position shift in the running direction sometimes occurs because the inclination angles given by two belt rolls deviate due to their accuracy or for other reasons. In such a case, after zigzag movements and/or corrections required therefor, and positional shifts in the running direction between opposite side edges of the belt and/or corrections required therefor are found, calculation is made using these values so that the zigzag movements and positional shifts in the running direction fall within an allowable range, and the proper values for the belt tilt angle Θ 1 and the tension difference ΔP of the side edges of the belt are determined. FIG. 9 shows the construction of such a single facer. Unlike the single facer shown in FIG. 8, signals from a transmission type photoelectric tube 30 for detecting sideway movements of the belt and transmission type photoelectric tubes 34a and 34b for detecting positional shifts in the running direction between the belt edges are once inputted to a computing device 35. Their correction amounts are determined by this computing device 35, and signals are sent to respective control units 31a and 31b to determine the belt angle Θ 1 and the tension difference ΔP. Thereupon, even if the belt angle Θ 1 and the tension difference ΔP affect the corrections of sideway movements of the belt and relative positional shifts between the two belt edges in an interrelating manner, the sideway movements and positional shifts can be corrected by means of the computing device. As described above in detail, according to the single facer of the last aspect of the invention, at least one pair of belt rolls of the rolls in contact with the endless belt are tilted with respect to the corrugating roll in the plane composed by these rolls, by which the endless belt can be moved in the width direction to correct the zigzag or sideway movement. By carrying out this control by using an automatic detecting device and a control unit, the effects of elimination of need for manpower and no dependence on operator's skill can be achieved.

Claims: A single facer including: a rotating corrugating roll (24) for corrugating a medium and for carrying a medium with paste being applied to top portions of corrugation thereof; an endless belt (23) for pressing a liner against the medium on the corrugating roll, at least a pair of belt rolls (21, 22) for giving tension to the endless belt and for running it, and a direction adjusting mechanism for changing a running direction of the endless belt with respect to a plane perpendicular to a rotating shaft of the corrugating roll within a running plane of the endless belt to correct zigzag movements in a width direction of the endless belt occurring as it runs, characterized in that the direction adjusting mechanism is adapted to change the running direction of the endless belt (23) from a direction perpendicular to the rotating shaft of the corrugating roll (24) while the angle between the rotating shafts of the pair of belt rolls (21, 22) is substantially maintained. A single facer according to claim 1, wherein the direction adjusting mechanism connects shaft ends of the at least one pair of belt rolls (21, 22) on both right and left sides of the belt rolls by means of bridges (27a, 27b), one bridge having a supporting point (32), and the belt rolls are tiltable around the supporting point, so that the running direction of the belt has a non-zero angle Θ with respect to the direction perpendicular to the rotating shaft of the corrugating roll (24) (Fig. 1, 6, 9). A single facer according to claim 1, wherein the direction adjusting mechanism connects ends of rotating shafts of the at least one pair of belt rolls (21, 22) on only one side of the belt rolls by means of a bridge (27), and the belt rolls are tiltable around ends of rotating shafts on the other side which ends are rotatably fixed so as to act as supporting points (32), so that the running direction of the belt (23) has a non-zero angle Θ with respect to the direction perpendicular to the rotating shaft of the corrugating roll (24) (Fig. 3). A single facer according to claim 1, wherein the direction adjusting mechanism rotatably locks the ends of the rotating shafts of the at least one pair of belt rolls (21, 22) on one side, a separate angle adjusting device (25) is installed at the end of each rotating shaft on the other side, and the belt rolls are moved, so that the running direction of the belt has a non-zero angle Θ with respect to the direction perpendicular to the rotating shaft of the corrugating roll (24) (Fig. 4). A single facer according to any of claims 1 to 4, which is further provided with a tension adjusting mechanism (28a, 28b) for changing an angle Θ 1 between the rotating shafts of the pair of belt rolls (21, 22) to adjust relative tension between opposite side edges of the endless belt (23) (Fig. 7). A single facer according to claim 5, wherein the tension adjusting mechanism comprises detection markings (33) located near side edges of the endless belt (23); detectors (34) for detecting positions of the detection markings in the belt running direction; a control unit (31a) for inputting outputs of the detectors; and a direction adjusting device (25) for tilting shafts of the belt rolls (21, 22) installed on at least one of the rolls and connected to the control unit, by which the direction adjusting device for the rotating shaft of the belt roll is controlled to change the direction of the rotating shaft of the at least one roll (22). A single facer according to claim 2 or 3, wherein at least one of the bridges (27a, 27b) has a length adjusting mechanism (28a, 28b) for changing the length of the bridge as a tension adjusting mechanism for adjusting tension balance between side edges of the endless belt (23). A single facer according to claim 1, which further comprises a detector (30) for detecting a displacement (s) of the endless belt (23) in a width direction; and a control unit (31a) for operating and controlling the direction adjusting mechanism (25) in accordance with a positional correction in the width direction of the endless belt which is calculated on the basis of signals from the detector. A single facer according to claim 5, which further comprises a displacement detector (30) for measuring a displacement of the endless belt (23) on the belt roll (22) in a width direction; detection markings (33a, 33b) located near opposite side edges of the endless belt (23); position detectors (34a, 34b) for measuring a relative positional shift (s) between the detection markings in the belt running direction; a direction control unit (31a) for operating the direction adjusting mechanism (25) in accordance with a positional correction in the width direction of the endless belt, which is calculated on the basis of a signal from the displacement detector; and a tension control unit (31b) for operating the tension adjusting mechanism (28a, 28b) in accordance with outputs from the position detectors (Fig. 9). A single facer according to claim 9, wherein the direction and tension control units (31a, 31b) operate the direction adjusting mechanism (25) and the tension adjusting mechanism (28a, 28b) in accordance with both the positional correction and the outputs from the position detectors. A single facer according to claim 10, wherein functions of the direction and tension control units are incorporated into one control unit (35).

Inventors: ANDO MAKOTO, KOHNO KAZUKIYO, MARUYAMA YOSHIAKI, SEKI YUKUHARU, TANIMOTO KOHSHI, ANDO, MAKOTO, KOHNO, KAZUKIYO, MARUYAMA, YOSHIAKI, SEKI, YUKUHARU, TANIMOTO, KOHSHI, Ando, Makoto, c/oMitsubishi Jukogyo K.K., Kohno, Kazukiyo, c/oMitsubishi Jukogyo K.K., Maruyama, Yoshiaki, c/oMitsubishi Jukogyo K.K., Seki, Yukuharu, c/oMitsubishi Jukogyo K.K., Tanimoto, Kohshi, c/oMitsubishi Jukogyo K.K.
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1994
Main classification: B31F1
IPC codes: B31F1, B32B38, B32B37